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arXiv · 1210.3852

Unidentified sources in the Fermi-LAT second source catalog: the case for DM subhalos

Hannes-S. Zechlin·Dieter Horns
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Abstract

The Large Area Telescope (LAT) aboard the Fermi satellite allows us to study the high-energy gamma-ray sky with unprecedented sensitivity. However, the origin of 31% of the detected gamma-ray sources remains unknown. This population of unassociated gamma-ray sources may contain new object classes, among them sources of photons from self-annihilating or decaying non-baryonic dark matter. Fermi-LAT might be capable to detect up to a few of these dark matter subhalos as faint and moderately extended gamma-ray sources with a temporally steady high-energy emission. After applying corresponding selection cuts to the second year Fermi catalog 2FGL, we investigate 13 candidate objects in more detail including their multi-wavelength properties in the radio, infrared, optical, UV, and X-ray bands. For the gamma-ray band, we analyze both the 24-month and 42-month Fermi-LAT data sets. We probe the gamma-ray spectra for indications of a spectral cutoff, which singles out four sources of particular interest. We find all sources to be compatible with a point-source scenario. Multi-wavelength associations and, in particular, their infrared color-color data indicate no source to be compatible with a dark matter origin, and we find the majority of the candidates to probably originate from faint, high-frequency peaked BL Lac type objects. We discuss possibilities to further investigate source candidates and future prospects to search for dark matter subhalos.

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Hannes-S. Zechlin, Dieter Horns. 2015-05-26. Unidentified sources in the Fermi-LAT second source catalog: the case for DM subhalos. https://doi.org/10.1088/1475-7516%2F2012%2F11%2F050

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